Don't specify an egress node - connect directly to a node that you want to egress public traffic out of - define it as an Ingress Node - your ExternalClient (the netmaker ExternalClient will be mostly correct) - (you may need to configure NAT on the ingress/egress node) then update the AllowedIPs to the public block (being sure to filter out the Node you are connecting to's IP address (the endpoint in the ExternalClient config))